Behavior of Unidirectional Sandwich Panels with a Multi-Skin Construction or a Multi-Layered Core Layout-High-Order Approach

Abstract

The behavior of a unidirectional sandwich panel that consists of a multi-skin construction and a "soft" core is presented. In addition, a unidirectional sandwich panel with a core made of various layers, a multi-layered core, is discussed. The formulation is comprehensive, rigorous, and uses a variational approach that yields the field equations along with the appropriate boundary conditions for beams and unidirectional panels (wide beams). The governing equations for the two cases are presented for skins made of laminated composites with a general stacking sequence, and for a multi-layered core made of layers of isotropic or orthotropic materials. Typical panels that consist of a multi-skin construction are numerically studied. A unidirectional sandwich panel that has an edge with a cut-off is investigated and the involved stress concentration is examined as well. The effect of additional skin layers at mid height of the panel is presented and compared with an ordinary panel that consists of two skins. The multi-layered core layout is used to numerically study the effect of delamination between the layers of the core on the general behavior of the unidirectional sandwich panel and the stress concentration involved.

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References

1. Chen, Q. and Levy, C. , "Vibration characteristics of partially covered double-sandwich cantilever beam," AIAA Journal, Vol.34, no. 12, Dec. 1996, pp. 2622-2626.

2. Ray, K. and Kar, R. C. , "Parametric instability of dual-cored sandwich beam," Computers & Structures, Vol. 61, no. 4, 1996, pp. 665-671.

3. Ray, K. and Kar, R. C. , "Parametric instability of partially covered sandwich beams," Journal of Sound and Vibration, Vol. 197, no. 2, 1996, pp. 137-152.

4. Kung, S. W. and Singh, R. , "Complex eigensolutions of rectangular plates with damping patches," Journal of Sound and Vibration, Vol. 216, no. 1, 1998, pp. 1-16.

5. Noor, A. K. and Barton, W. S. , "Assessment of shear deformation theories for multi-layered composite plates," Applied Mechanics Reviews, Vol. 42, no. 1, 1989, pp. 1-12.

6. Carrera, E. , "A refined multi-layered finite element model applied to linear and non-linear analysis of sandwich panel," Composites Science and Technology, 58, 1998, pp. 1553-1569.

7. Hussein, R. , "Sandwich plates with interlayer slips," Journal of ASCE, EM Division, Vol. 110, no. 4, Apr. 1984, pp. 493-506.

8. Burton, W. S. and Noor, A. K. , "Structural analysis of the adhesive bond in a honeycomb core sandwich panel," Finite Elements In Analysis and Design, 26, 1997, pp. 213-227.

9. Thomsen, O. T. , "Local bending induced by tapering of face-laminates in CFRP-sandwich panels," Allen, H.G. (Ed.), Sandwich Construction 3, Vol. 1, pp. 215-230, EMAS, U.K., 1995.

10.

10. Frostig, Y. , "Behavior of Delaminated Sandwich Beams with Transversely Flexible Core-High Order Theory," Composite Structures Journal, Vol. 20, Jan. 1992, pp. 1-16.

11.

11. Frostig, Y. , Baruch, M. , Vilnai, O. , Sheinman, I.

"High-Order Theory for Sandwich-Beam Bending with Transversely Flexible Core,"

Journal of ASCE, EM Division, Vol. 118, No. 5, May 1992, pp. 1026-1043.

12.

12. Frostig, Y.

"On Stress Concentration in the Bending of Sandwich Beams with Transversely Flexible Core,"

Composite Structures, 24, 1993, pp. 161-169.

13.

13. Frostig, Y.

"High-Order Behavior of Sandwich Beams with Flexible Core and Transverse Diaphragms,"

Journal of ASCE, EM Division, Vol. 119, no. 5, May 1993, pp. 955-972.

14.

14. Frostig, Y. , Baruch, M. , "High-Order Buckling Analysis of Sandwich Beams with a Transversely Flexible Core," Journal of ASCE, EM Division, Vol. 119, no. 3, March 1993, pp. 476-495.

15.

15. Frostig, Y. , Baruch, M. , "Free Vibration of Sandwich Beams with a Transversely Flexible Core: A High Order Approach," Journal of Sound and Vibration, 176(2), 1994, pp. 195-208.

16.

16. Peled, D. and Frostig, Y.

"High-Order Bending of Sandwich Beams with a Transversely Flexible Core and Nonparallel Skins,"

Journal of ASCE, EM Division, Vol. 120, no. 6, June 1994, pp. 1255-1269.

17.

17. Frostig, Y. and Shenhar I.

"High-Order Bending of Sandwich Beams with a Transversely Flexible Core and Unsymmetrical Laminated Composite Skins,"

Composite Engineering, An International Journal, Vol. 5, no. 4, pp. 405-414, 1995.

18.

18. Peled, D. and Frostig, Y.

"High-Order Bending of Piecewise Uniform Sandwich Beams with a Tapered Transition Zone and a Transversely Flexible Core,"

Composite Structures, 31, 1995, pp. 151-162.

19.

19. Frostig, Y. and Baruch M.

"Localized Load Effects in High-Order Bending of Sandwich Panels with Transversely Flexible Core,"

Journal of ASCE, EM Division, Vol. 122, no. 11, 1996, pp. 1069-1076.

20.

20. Shenhar, I. , Frostig, Y. and Altus, E.

"Map Failure of Sandwich Beam with Unsymmetrical Laminated Composite Skins and a Transversely Flexible Core,"

Composite Structures, Vol. 35, no. 2, June 1996, pp. 143-152.

21.

21. Frostig, Y.

"Hygrothermal (Environmental) Effects in High-Order Bending of Sandwich Beams with a Flexible Core and a Discontinuous Skin."

Composite Structures, Vol. 37, no. 2, February 1997, pp. 205-221.

22.

22. Bozhevolnaya, E. and Frostig Y. , "Nonlinear Closed-Form High-Order Analysis of Curved Sandwich Panels," Composite Structures, Vol. 38, no. 1-4, 1997, pp. 383-394.

23.

23. Frostig, Y.

"Buckling of Sandwich Panels with a Transversely Flexible Core High-Order Theory,"

International Journal of Solids and Structures, Vol. 35, Nos. 3-4, 1998, pp. 183-204.

24.

24. Frostig, Y.

"Bending of Curved Sandwich Panels with Transversely Flexible Cores Closed-Form High-Order Theory,"

Journal of Sandwich Structures & Materials, Vol. 1 January 1999, pp. 4-41.

25.

25. Thomsen, O. T. , Frostig Y. and Mortensen, F. , "Interface Failure at Ply Drops in CFRP/Sandwich Panels," to appear in Journal of Composite Materials, Vol. 7, 1999.

26.

26. Sokolinsky, V. and Frostig, Y. "Effects of Boundary Conditions in High-Order Buckling of Sandwich Panels with a Transversely Flexible Core," to appear in Journal of ASCE, EM Division, 1999.

27.

27. Thomsen, O.T. and Frostig, Y.

"Localized Bending Effects in Sandwich Panels: Photoelastic Investigation versus High-Order Sandwich Theory Results,"

Composite Structures, Vol. 37, no. 1, January 1997, pp. 97-108.